Selectron radio control unit



13, 1964 o. 5. BLACK 3,153,181

SELECTRON RADIO comaor. UNIT Filed Feb. 9, 1962 r0 lzAom f w gy /G. 1

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United States Patent "ice 3,153,181 SELEQTRQN RADIO CUNTRQL UNIT Owen 5.Black, 4920 Cypress Ave, Carmichael, Calif. Filed Feb. 9, W62, 61. No.172,198 6 Claims. (Cl. Elih -lid) This invention relates to a radio waveresponsive remote control unit. The unit is particularly adapted for usein conjunction with the remote control equipment in model airplanes andboats, which equipment is operated from distant locations.

The remote control equipment at present in use is in some cases of themultiple channel type, where the transmitter and the receiver are tunedto a radio frequency and audio signals are transmitted to give two ormore control channels. An individual relay is provided in each controlchannel. Energization of one relay causes a servo motor to run in onedirection and energization or" a second relay causes the servo motor torun in the opposite direction. The circuit connections of the servomotor to the relays are so arranged that when neither relay is energizedthe servo motor seeks a central position, due to the operation of aswitch within the latter.

In other cases the remote control equipment is of single channel typebut is cyclic in operation. In the operation of this equipment it mustgo to the limit of both controls, to the right, then to the left, beforereturning to the neutral position. In model airplanes and boats whererapid starts, stops and reversals of the ailerons and rudders arerequired, this develops into an erratic pattern of operation.

The object of the present invention is to provide a remote control unitwhich may be added to the present multiple channel remote servoequipment used on model airplanes and boats and which will convertsameto single channel operation.

Another object of the present invention is toprovide a remote controlunit which may be used with the present remote control servo equipmenton model airplanes and boats and which provides that any degree ofcontrol may be held in position as desired.

A further object of the present invention is to provide a remote unitfor use in conjunction with the present remote control servo equipmentused in model airplanes and boats in which it is possible to reach thelimit of control in one direction of operation without going in theother direction of operation.

An additional object of the present invention is to provide a remotecontrol unit for use in association with the present remote controlequipment used on model airplanes and boats working on a single freqency channel, in which control movement in either direction may berepeated at will, without having to go through undesirable controlmovement in the opposite direction.

Still other objects, advantages and improvements will become apparentfrom the following description, taken in connection with theaccompanying drawings, in which:

FIGURE 1 is a circuit diagram, with mechanical connections shownschematically, of the remote control unit according to the presentinvention;

FIGURE 2 shows a modified circuit diagram in which any degree of controlposition may be held, as desired;

FIGURE 3 shows a switch, which operates from the servo motor through afluid coupling and which replaces 3,l53,l8l Patented Oct. 13 1964 one ofthe relays in the circuit according to FIGURE 1 or FIGURE 2; and

FIGURE 4 shows a switch which is operated from the servo motor throughan escapement mechanism, and which likewise replaces one of the relaysin the circuit diagram according to FIGURE 1 or FIGURE 2.

Referring now to the drawings in detail and to FIG- URE 1 in particular,the reference numeral ll) here designates the winding of a first relayRy-ll. This is a single pole, double-throw relay. This winding 10 isconnected by conductors 11 and 12 to a radio receiving apparatus (notshown), which is located in a suitable position in the model airplane oron the boat, and receives signals from a suitable radio transmittingapparatus (also not shown), which is located in a suitable position onland. This relay has an armature 14, which engages a fixed contact 13,when the relay is in the de-energized condition, and a fixed contact 15,when the relay is energized.

The circuit also includes a second relay Ry-2, the winding of which isdesignated by the reference numeral 16. This is likewise a single pole,double-throw relay having an armature 19, which engages a fixed contact18 when the relay is in the de-energized condition, and a fixed contact20 when the relay is energized. The armature 19 of the relay Ry2 isconnected by a conductor 26 to the normally open contact 15 of the relayRy-l. The winding 16 of the relay Ry2 is connected in parallel with thearmature of a servo motor M, over a conductor 29 on one side and over aconductor 39 and through a diode rectifier D-1 on the other side. Acapacitor C1 is connected across the winding 16 and provides a timedelay factor for the voltage developed across the winding 16.

One side of the winding 16 of the relay Ry2 is connected by theconductor 29, and one side of the armature of the servo motor M isconnected by conductors 31 and 32 to the positive terminal of a batteryB-1 and the negative terminal of a battery B-Z. These batteries 13-1 andB-Zpretera'oly each have an electro-motive force of three (3) volts. Theother side of the winding 16 of the relay through the diode D1 and theother side of the armature of the servo motor are connected by aconductor 33 to the armature 14 of the relay Ry1.

The servo motor M has a drive shaft 34 and also a duplex built-inselector switch SW-1 and SW2, the two components of which are theequivalent of single pole, double-throw switches. Both components areoperated in unison from the drive shaft 34 of the servo motor M througha mechanical linkage 35. The switch component SW-l includes a firstfixed contact 36,21 wiper blade 37, and a second fixed contact 38. Thewiper blade 37 continuously rides over the first fixed contact 35,except in its extreme positions to the left and right (FIGURE 1); italso rides over the second fixed contact 38 in its movement toward theright. Similarly, the switch component SW-2 includes a first fixedcontact 42, a wiper blade 43, and a second fixed contact 44. The wiperblade 43 likewise continuously rides over the first fixed contact 42,except in its extreme position to the right; it also rides over thesecond fixed contact 44 in its movement toward the left.

The negative terminal of the battery 3-1 is connected by a conductor 39to the wiper blade 37 of the selector switch component SW-l; similarly,the positive terminal of the battery 3-2 is connected by a conductor 40to the wiper blade li-5 of the selector switch component, SW2.

The first fixed contact 36 of the selector switch component SWl isconnected by a conductor 27 to the normally closed contact 13 of therelay Ry-Z; likewise, the first fixed contact 42, of the selector switchcomponent SW2 is connected by a conductor 23 to the normally opencontact 20 of the relay Ry-Z. The second fixed contact 38 of theselector switch component SW-Jl and the second fixed contact 44 of theselector switch component SW-Z are interconnected by a conductor 45 andare connected by a conductor 46 to the normally closed contact 13 of therelay Ry-l.

In the circuit described, the two relays Ry-l and Ry-Zt are connected intandem relationship. This arrangement allows the servo motor M to seekits neutral position, just as in the multiple channel equipment atpresent known. However, in the circuit according to the presentinvention, only the relay Ry-l is controlled by radio impulses, therelay Ry-2 being controlled by the current flowing through the armatureof the servo motor M.

In operation, the selector switch components SW-1 and SW-Z function toreturn the servo motor M to its neutral position in the followingmanner: Let it be assumed that both of the relays Ry-l and Ry-Z are intheir deenergized positions, as shown in FIGURE 1. It will be noted thatthe wiper blade 37 is always on the first fixed contact 3-6 of theselector switch component SW-l, except when it is in the extremeposition to the left or right (FIGURE 1), and likewise the wiper blade43 is always on the first fixed contact 42 of the selector switchcomponent SW-Z, except when it is in the extreme position to the right.In the neutral position, however, the wiper blade 37 is free of thesecond fixed contact 38 of the selector switch component SW-l and thewiper blade 43 is also free of the second fixed contact 44 of theselector switch component SW-Z. For rotation of the servo motor M in onedirection, which is hereinafter termed the Primary direction, thecircuit is from the positive terminal of the battery B4, over theconductors 32 and 31, through the armature of the motor, over theconductors 30 and 33 to the armature 14 and fixed contact 13 of therelay Ry-l, over the conductors 4-6 and 45 to the second fixed contact38, wiper blade 37 and first fixed contact 36 of the selector switchcomponent SW-T, and over the conductor 39 to the negative terminal ofthe battery B-ll. Similarly, for rotation of the servo motor M in theopposite direction, which is hereinafter termed the Secondary direction,the circuit is from the positive terminal of the battery B4), over theconductor 4 3' to the wiper blade 43 and the second fixed contact 44 ofthe selector switch component SW-Z, over the conductors 45 and 416 tothe normally closed contact 13 and armature 14 of the relay Ry-l, overthe conductors 33 and 39, through the armature of the servo motor, andover the conductors 31 and 32 to the negative terminal of the batteryB-2.

It will be noted that the wiper blade of the selector switch componentSW4 and the wiper blade 43 of the selector switch component SW-Z aremechanically interconnected by the linkage 35 and are driven from theshaft 34 of the servo motor M. In both of the above-described circuits,if the wiper blade 37 is free of the second fixed contact 38 of theselector switch component SW-dl and the wiper blade 43 is simultaneouslyfree of the second fixed contact 44, of the selector switch componentSW-Z, the respective circuit is open and there is no flow of current.This is the neutral position of the servo motor M.

It the servo motor M is rotated, in a manner to be later described, tomove the wiper blade 3'7 of the switch component SW-l to the right, thiswiper blade will ride onto the second fixed contact 38 of the switchcomponent.

The first described circuit above will now be completed from thepositive terminal of the battery B4, over the conductors 32 and 31,through the armature of the servo motor, over the conductors 30 and 33to the armature l4 and the normally closed contact 13 of the relay Ry-l,over the conductors 46 and 45 to the second fixed contact sale].

38, the wiper blade 37 and first fixed contact 36 of the switchcomponent SW41, and over the conductor 33 to the negative terminal ofthe battery B-l. The servo motor M will now be rotated in the reversedirection and the wiper blades 3'7 and 43 of the selector switchcomponents SW4 and SW-Z, respectively, will be shifted to the neutralposition.

If, however, the servo motor M is rotated in the opposite direction,again in a manner to be later described, to move the wiper blade 43 ofthe switch component SW-2 to the left, this wiper blade will ride ontothe second fixed contact 44 of the switch component. The seconddescribed circuit above will now be completed from the positive terminalof the battery B2, over the conductor 43 to the wiper blade 43, firstfixed contact 42 and second fixed contact 44 of the selector switchcomponent SW-2, over the conductors 4:5 and 4-6 to the normally closedcontact 13 and armature M of the relay Ry-l, over the conductors 33 and39, through the armature of the servo motor M, and over the conductors31 and 32 to the negative terminal of the battery 13-2. The servo motorM will now be rotated in the reverse direction and the wiper blades 37and 43 of the selector switch components SW-l and SW-Z, respectively,will be shifted to the neutral position.

The above explains the neutralizing action of the servo motor M. Itshould be noted that this neutralizing action takes place when the relayRy-1 is in its de-energized condition, without regard to whether therelay Ry-2 is open or closed.

As stated above, the wiper blade 37 is on the first fixed contact 36 ofthe selector switch component SW-l and the wiper blade 43 is on thefirst fixed contact 4 2 of the selector switch component SW2, when theservo motor M is at rest. Also, relay Ry-Z is closed on the fixedcontact 18. If relay Ry-l is now energized, due to a signal beingreceived from the radio receiving set (not shown) over the conductors 11and 12, it closes on the normally open contact 15. A circuit is nowcompleted from the positive terminal of the battery 13-11, over theconductors 32 and 31, through the armature of the servo motor M, overthe conductors 3b and 33 to the armature 14 and fixed contact 15 of therelay R 4, over the conductor 26 to the armature 19 and normally closedcontact 13 of the relay Ry2, over the conductor 27 to the first fixedcontact 36 and the wiper blade 37 of the selector switch component SW4,and over the conductor 39 to the negative terminal of the battery 3-1.The polarity of the voltage across the servo motor M is such that thediode rectifier D-l blocks the flow of current over the conductor 3b tothe winding 16 of the relay Ry-Z and this relay remains de-energized.The servo motor M will rotate and drive the wiper blade 37 to the leftuntil it runs off the left end of the first fixed contact 36 of theselector switch component SW]l. This is one extreme position of theservo motor M. As stated above, rotation of the servo motor in thisdirection is termed the primary direction; the rotation in the oppositedirection is termed the secondary direction. Since the energizingcircuit of the servo motor M is interrupted at this stage through theselector switch component SW-ll, the motor will remain in this positionas long as relay Ry-l is held energized. When the relay Ry-l istie-energized, the circuit for returning the servo motor M to itsneutral position is restored, as described above. The servo motor M thenruns in the reverse direction to the neutral position, when the wiperblades 37 and 43 are ofi the second fixed contacts 33 and d4 of theselector switch components SW-El and SW-Z, respectively. During thisreturn to neutral position, the polarity of the voltage across the servomotor M is reversed from that during rotation of the servo motor to theprimary position. The current can now flow through the parallel circuitcomprised by the conductor 30, diode rectifier D4, winding 16 of therelay Ry2, and over the conductor 29. The capacitor 0-1 is energizingcircuit of the motor being interrupted through the selector switchcomponents SW-l and SW-Z, and relay Ry-2 returns to its de-energizedcondition with its armature 19 on the contact 18. If, however, the relayRy1 is again energized during return movement of servo motor M to theneutral position, a circuit will be completed as follows: From thepositive terminal of the battery B-Z, over the conductor 40 to the wiperblade 43 and first fixed contact 42 of the selector switch componentSW4, over the conductor 28 to the normally open contact 20 and armatureof the relay Ry-Z, over conductor 26 :to the normally open contact andarmature 14 of relay Ry1, over conductors 33 and 30, through thearmature of the servo motor, and over the conductors 31 and 32 to thenegative terminal of the battery 13-2. Since the polarity of the voltageacross the armature of the servo motor M is still such that relay Ry-Zis energized, the servomotor will rotate until the wiper blade 43 ismoved to its secondary extreme position, that is beyond the right end ofthe first fixed contact 42, of the selector switch component SW-2. Atthe same time, the wiper blade 37 is also moved to its secondary extremeposition, that is beyond the right end of the first fixed contact 36 ofthe selector switch component SW-1. At this stage, the energizingcircuit of the servo motor M is interrupted and relay Ry-Z isde-energized, its armature 19 closing on fixed contact 18. With thewiper blade 37 oil the first fixed contact 36 of the selector switchcomponent SW4, the energizing circuit of the servo motor M isinterrupted, and the servo motor remains in its secondary extremeposition, as long as relay Ry-l is held energized by continuousreception of radio signals.

To achieve the result of obtaining the control direction required,without going in the opposite unwanted control direction, the radiotransmitting set is keyed as follows: A radio signal comprised of a longsignal on and hold, will initiate rotation of the servo motor -M in theprimary direction and will hold it in the extreme primary position. Thecessation of the signal will allow the servo motor M to return to itsneutral position. To produce rotation of the servo motor to thesecondary con-trol position, the radio signal is applied to start therotation of the servo motor in the primary direction, and then thesignal is released. Before the servo motor reaches the neutral position,the radio signal is reapplied and held on. The servo motor will move thewiper blades 37 and 43 of the selector switch components SW-l and SW-Z,respectively, through the neutral position and to the secondary extremeposition, as previously described. It the radio signal is released andthen immediately re-applied, while the servo motor is moving the wiperblades 37 and 43 toward the extreme secondary position, the direction ofrotation of the servo motor Will be reversed, and it will rotate to theextreme control position. This operation allows for quick reversal ofthe control movement of the servo motor, if needed.

The circuitaccording to FIGURE 2 provides for holding any degree ofcontrol in position, as may be desired. This circuit according to thismodification diilers from that of FIGURE 1 in three respects. The firstfixed contacts and 42a do not overlap the second fixed contacts 38 and Min the line of travel of the wiper blades '37 and 43 of the selectorswitch components SW-l and I Jiper blade 43 does ride over both thefirst fixed contact 42a and the second fixed contact 54 of the selectorswitch component SW-Z for a short period, when moving in the primarydirection. I l

The relay Ry-Z of FIGURE 2 has two armatures 19 and 23, which areinterconnected by a link 21, and two sets of contacts It) and 20 and 22and 24. When the relay is in its tie-energized condition, the armature19 is closed on the contact 18 of the first set, as in the circuit ofFIGURE 1, and the armature 23 is on a rest contact 22; also, when therelay is energized, the armature 19 is closed on the contact Zit, againas in the circuit of FIG- URE l, and. the armature Z3 is on a contact24. The

conductor 45, which interconnects the second fixed contacts 38 and 44 ofthe selector switch components SW4 and SW-Z, respectively, and thenormally closed contact 135 of the relay Ry l, is extended and connectedto the normally open contact 24.

A second diode rectifier D-Z is connected by a conductor 25 to thesecond armature 23 of the relay Ry-2 and to the conductor 3-0 from thearmature oi": the servo motor M and first diode rectifier D-1 to oneside of the winding 16 of the relay.

The circuit operation of FIGURE 2 is very much the same as that of thecircuit according to FEGURE 1. An exception is that the radio signal forthe selection of direction must be applied during the period when thewiper blade 37 is on the first fixed contact 36a of the selector switchcomponent SW-l, or when the wiper blade 43 is on the first fixed contact42a and the second fixed contact 44 of the selector switch componentSW2. After a control direction has been determined by a radio signal andthe servo motor M has rotated beyond the point where the wiper blade 37is riding simultaneously on the fixed contacts 36a and 38 of theselector switch component SW-i, or the wiper blade 43 is ridingsimultaneously on the fixed contacts 42a and 4d of the selector switchcomponent SW43, the. rotation of the servo motor M may he stopped byinterrupting the radio signal momentarily and re-applying it. If theservo motor M is rotating so as to move the wiper blades and 4301" theselector switch components SW-l and SW-Z, respectively, in the primarydirection, relay Ely-2 is still in the normal or open condition with itsfirst armature 1 9 on the contact 18 and its second armature on the restcontact 22, Wiper blade 37 is riding over the first fixed contact 36a ofthe selector switch component SW-l, and wiper blade 43 is riding overthe first fixed contact 42a and the second fixed contact 44 of theselector switch component SW-Z. Momentary cessation of the signal causesthe servo motor M to start to rotate and shift the Wiper blades 37 and43 of ti e selector switch components SW-1 and SW-Z, respectively, tothe neutral position. This completes the energizing circuit for therelay R3 4, the second armature 23 closing on the normally open contact24. A circuit is nowcompleted from the positive terminal of the batteryB-Z, over the conductor slit, to the wiper blade 4-3 and second fixedcontact 44 of the selector switch component SW-Z, over the conductor 45to the contact 24 and second armature 23 oi the relay Ry-Z, over theconductor 25' and through the second diode rectifier D-2, through thewinding 16 of the relay Ry-Zu, and over the conductors Z9, 31, and tothe negative terminal of the battery B-Z. The current thus fiowingthrough the Winding 16 of the relay Ry2 holds the relay closed, as longas the wiper blade 45 is riding on the second fixed contact 44- of theselector switch component SW-Z.

if the radio signal is now re-applied, relay Ry-l is energized and itsarmature l4 closes on the contact 15, and the energizing circuit for theservo motor M is partially completed over the conductor 26, armature 19and contact 2d of the relay lly-Z, and over the conductor 2,8 to thefirst fixed contact 42a of the selector switch component-Si -2'. Since,however, the wiper blade 43 is not on the first fixed contact die, theenergizing circuit of the servo motor M is incomplete at this point, andno current'tlows in this circuit. The servo motor M, therefore, re:iains in the instantaneous position that it was in when the radiosignal was re-applied. This could be at any position of rotation of theservo motor M in its travel while moving the wiper blades 57 and 4-3 ofthe selector switch components SW-l and SW41, respectively, to theneutral position. Successive releases and re-applications of the signalcause the servo motor M to rotate and move the wiper blades 37 and 43 ofthe selector switch compo nents SW-l and SW-Z, respectively, in shortsteps until the neutral position is reached and the wiper blade 43 isoff the second fixed contact of the selector switch component SW-Z. Thisbreaks the holding circuit through the winding 16 of the relay Ry2 andthe second diode rectifier D-2 and the servo motor M remains in theposition with the wiper blades 37 and 43 in neutral. If the servo motorM is rotating to move the wiper blades 37 and 43 in the secondarydirection, after passing the point where the wiper blade 37 issimultaneously on the first fixed contact 36 and the second fixedcontact 38 of the selector switch component SW-ll, and if the radiosignal is interrupted, relay Ryl is released and its armature l4 closeson the contact "13, which completes the energizing ci cuit of the servomotor M and the latter rotates to return the wiper blades 37 and 43' ofthe selector switch components SWl and SEW-2 to the neutral position. Ifnow the radio signal is resumed, relay Ry-1 is again energized, itsarmature 14- closing on the contact 15, and completing the circuit fromthe positive terminal of the battery B-l over the conductors 32 and 31to the servo motor M and over the conductors 3'? and 33 to the armatureand contact 15 of relay Ryl, over conductor 26 to armature i9 andcontact 13 of relay Ry2;, over conductor 27 to the first fixed contact35a of the selector switch component SW-l. Since the wiper blade 37 isnot at this time on the first fixed contact 36a, the energizing circuitof the servo motor M is broken at this point, no current flows in thecircuit and the motor ceases to rotate at this particular position inits sequence of movement.

In this return rotation of the servo motor M to the neutral positionwith the wiper blade 37 on the second fixed contact 38 of the selectorswitch component SW-l, the first diode rectifier D L blocks the flow ofcurrent over the conductor 29, through the winding 16 of the relay Ry-Z,de-energizing this relay.

in the circuits of FIGURES l and 2, the relay Ry-ll is responsive to thereception of radio signals and the relay Ry2 is responsive to thecurrent flowing through the armature of the servo motor M. in thecircuit of F1 URE 1 the relay Ry-Z can be replaced by a mechanicallyoperated switch. T he only requirement for such a switch is that itshall have contacts which are normally closed when the servo motor M isstopped or rotating to move the wiper blades 57 and d3 of the selectorswitch components SW4 and SW-Z, respectively, in the primary direction,and a normally open contact that closes when the servo motor drives inthe secondary direction. T he basic idea is still the operation of theswitch, which replaces the relay Ry2, by the servo motor M in a singlechannel remote control unit in the desired manner.

FIGURE 3 shows a fluid coupling for operating a switch of the typedescribed. A cylindrical casing 53 is mounted on and for rotation withthe shaft 34 of the servo motor M and has radially positioned blades 4n?on its inner circumferential wall. A rotor 59 is freely mounted forrotation on the shaft and has radially positioned blades 51 on itscircumference, which are compl mentary to the radially positioned blades.9 on the inner circumferential wall of the casing 47. The annular spacebetween the cylindrical casing and the rotor is filled with fluid,preferably oil. A semi-cylindrical cam 52 is mounted on the rotor 5t andlikewise for free rotation on the shaft This cam is biased to theposition where its diameter is horizontal by a coil tension spring 53,which latter is secured at one end to a corner of th earn and at itsother end to a suitable fixed support 54. A follower lever 55 rests atone end on the semi-cylindrical cam 52 and normally at the crest of thelatter, so that it will be raised by the cam when the shaft 3 is rotatedto move the wiper blades 37 and 43 of the selector switch componentsSW-i and SW2 in the secondary direction. This follower lever is pivotedalong its length at 56 on a base 57, which also rests on the support 54,or some similar support. A coiled tension spring 59 is connected at oneend to the follower lever 55 intermediate the cam 52 and the pivot 56,and at its other end this follower lever carries a blade 58. This bladenormally is against the rest contact 22 but, upon rotation of the shaft34 to move the wiper blades 37 and 53 of the selector switch componentsSW-l and SW2, respectively, in the secondary direction, it will close onthe normally open contact 24.

In the arrangement according to FIGURE 4, the fluid coupling 42lil isreplaced by an escapement gear 60 having teeth of thereon, which gear ismounted on and for rotation with the shaft 34 of the servo motor M. Thelever 55 here carries at its outer end an escapement fork 59, havingtransversely spaced arms 5% and 5% thereon which latter cooperate withthe escapernent gear 69. The operation of this escapement gear and forkmechanism is similar to that of the fluid coupling arrangement accordingto FEGURE 3.

Having now fully described my invention, what I claim as new and usefuland desire to secure by Letters Patent of the United States is:

1. An electrical control system for model boats and airplanes comprisinga reversible servo motor for operating a control element of the model,means for controlling the direction of rotation of said motor inresponse to signals transmitted through space comprising switch meanspositioned by said servo motor and operable in a first and seconddirection through a neutral position, a plurality of circuits completedthrough said switch means for energizing said servo motor, means forselectively energizing said circuits to impress a voltage of properpolarity across said servo motor including a first relay responsive tosaid signals, a second relay having a coil connected' in series with aunidirectional current means across said servo motor and an armaturemeans having a pair of contacts, one of said contacts being normallyclosed and the other contact being normally open and closed in responseto energization of said coil, means to delay the response of said secondrelay, said second relay means cooperating with contact means of saidfirst relay means to complete one of said circuits through said normallyclosed contact for energizing said motor to rotate in a first directionupon receipt of a single transmitted signal, and to complete a secondcircuit through the normally closed contact to operate the motor in theopposite direction in response to two signals transmitted in closesequence.

2. An electric control system as in claim 1, in which said time delaymeans comprises a condenser connected across the coil of said secondrelay.

3. An electrical control system as in claim 1, wherein said first relaymeans comprises an armature having a pair of contacts, one of saidcontracts being normally closed and connected to said switch means andthe other contact being normally open and closed in response to receiptof a transmitted signal, said other contact of the first relay beingconnected to the armature of said second relay means.

4. An electrical control system as in claim 3, wherein said servo motoroperates a second switch means comprising rotary actuating means, oneside of said switch means being attached by unidirectional current meansto one side of the coil of said second relay and the other side of saidswitch means being attached by conductor means to the switch of theswitching network to provide r 10 a circuit for holding any degree ofoperation of the conmeans operated by said servo motorto provide acircuit trol in position as desired during the operation thereof. forholding any degree of operation of the control in 5. An electricalcontrol system as in claim 3, wherein position as desired. said secondrelay has a second armature attached by uni- 6 An electrical ControlSystem as in Claim 3, wherein directional current means to one side ofthe coil of said i means fopselcctively energizing said circuits secondrelay and having a pair of contacts, one of said Pr two battenescontactsbeing normally closed and unattached to the circuitry and the othercontact being normally open References Clted m the file of thls patentand closed in response to energization of said coilof the UNITED STATESPATENTS second relay, said other contact of said second pair of 102,494,611 Eisenberg Jan. 17, 1950 contacts being connected by aconductor to said switch 3,002,140 Bonner Sept. 26, 1961

1. AN ELECTRICAL CONTROL SYSTEM FOR MODEL BOATS AND AIRPLANES COMPRISINGA REVERSIBLE SERVO MOTOR FOR OPERATING A CONTROL ELEMENT OF THE MODEL,MEANS FOR CONTROLLING THE DIRECTION OF ROTATION OF SAID MOTOR INRESPONSE TO SIGNALS TRANSMITTED THROUGH SPACE COMPRISING SWITCH MEANSPOSITIONED BY SAID SERVO MOTOR AND OPERABLE IN A FIRST AND SECONDDIRECTION THROUGH A NEUTRAL POSITION, A PLURALITY OF CIRCUITS COMPLETEDTHROUGH SAID SWITCH MEANS FOR ENERGIZING SAID SERVO MOTOR, MEANS FORSELECTIVELY ENERGIZING SAID CIRCUITS TO IMPRESS A VOLTAGE OF PROPERPOLARITY ACROSS SAID SERVO MOTOR INCLUDING A FIRST RELAY RESPONSIVE TOSAID SIGNALS, A SECOND RELAY HAVING A COIL CONNECTED IN SERIES WITH AUNIDIRECTIONAL CURRENT MEANS ACROSS SAID SERVO MOTOR AND AN ARMATUREMEANS HAVING A PAIR OF CONTACTS, ONE OF SAID CONTACTS BEING NORMALLYCLOSED AND THE OTHER CONTACT BEING NORMALLY OPEN AND CLOSED IN RESPONSETO ENERGIZATION OF SAID COIL, MEANS TO DELAY THE RESPONSE TO SAID SECONDRELAY, SAID SECOND RELAY MEANS COOPERATING WITH CONTACT MEANS OF SAIDFIRST RELAY MEANS TO COMPLETE ONE OF SAID CIRCUITS THROUGH SAID NORMALLYCLOSED CONTACT FOR ENERGIZING SAID MOTOR TO ROTATE IN A FIRST DIRECTIONUPON RECEIPT OF A SINGLE TRANSMITTED SIGNAL, AND TO COMPLETE A SECONDCIRCUIT THROUGH THE NORMALLY CLOSED CONTACT TO OPERATE THE MOTOR IN THEOPPOSITE DIRECTION IN RESPONSE TO TWO SIGNALS TRANSMITTED IN CLOSESEQUENCE.